The proposed research will measure the relative reinforcing value of two separate dimensions of cigarette smoke -- the sensory components (taste, aroma and tracheo-bronchial stimulation), and the pharmacologic actions of nicotine. These components of reinforcement will be dissociated with methods developed in the previous period of grant support. In one method, the sensory effects of cigarette smoke are presented with very little nicotine absorption by restricting inhaled smoke to the large, upper airways, where few smoke particles are deposited. Conversely, the pharmacologic effects can be presented with little sensory impact by greatly diluting the smoke prior to deep inhalations of large volumes. A method for eliciting the tracheo-bronchial "scratch" of smoke without any nicotine consists of delivering puffs of a fine aerosol containing a mildly irriating solution of citric acid. The subjective satisfaction and reduction in smoking behavior will be assessed after inhalations of the types just described. Changes in nicotine preference will be measured by allowing subjects to vary the nicotine concentration in each puff of smoke. Subjects' preference for the sensory versus pharmacologic components of smoke will also be studied after different satiation procedures. The hypothesis that sensory reinforcement arises from the association of stimuli with nicotine reinforcement will be tested by examining extinction after many nonreinforced presentations. The importance of temporal continguity in maintaining the conditioned reinforcing value of cigarette smoke will be evaluated by varying the time interval between sensory stimulation and nicotine reinforcement. The knowledge gained from this research may lead to more effective methods for reducing the incidence of cigarete smoking and related cardiovascular and pulmonary diseases.